Added apis to list commits by author and list the repos of an organization (including private ones)

Hi,

I have added apis for the following
* List the repos of organization (including the private ones).   The existing implementation does not list the private repos of an organization even with the appropriate scope permissions.
* List the commits by author and branch. [Note that both branch and sha are given as sha parameters to the url. I verified this manually. Got this solution from  stackoverflow : http://stackoverflow.com/questions/9179828/github-api-retrieve-all-commits-for-all-branches-for-a-repo 

Thank you,
vr100